Ordnance systems generally have three (3) separate units: (1) an input mechanism for initiating a timing operation representing a pre-selected delay, (2) a timing system for providing the pre-selected delay and (3) an output mechanism operated by the timing mechanism after the pre-selected delay. The input mechanism may take any one (1) of several different forms, all known in the prior art. For example, the input unit may provide (a) a gas input or a detonation input, (b) a mechanized input such as a lanyard, (c) an electrical input such as an electrical current, (d) an input based upon the attainment of a particular temperature or (e) an input based upon a particular pressure.
The timing systems in the prior art have generally been pyrotechnic. For example, a material has been combusted for a variable period of time dependent upon the characteristics of the combustible material. Such timing systems have had certain inherent disadvantages. For example, the timing has not been very accurate. Furthermore, the time delay provided by combustible materials has not been very long. The timing unit has also been disadvantageous because it has sometimes deteriorated with time and because it has sometimes provided an output at inappropriate times to actuate the output unit. These problems have occurred because the timing unit has been chemical. Such problems have been known to exist in the timing systems of the prior art for a relatively long period of time without any real ability to minimize the problems specified in this paragraph.
The output unit operated by the timing unit may have a number of different forms, all known in the prior art. For example, the output unit may constitute a cutter for a reefing line or may provide heat from a thermal battery. Generally, the input and output mechanisms have been more advanced in the prior art than the timing unit.